1. Field of Invention
This invention relates to a procedure for removing a water-insoluble finish from aramide fibers.
2. Description of Related Art
Aramide fibers are expensive in comparison to other synthetic fibers. Therefore, it is worthwhile to recycle the fibers following their use. The aramide fibers are often provided with a water-insoluble finish, e.g., with a cross-linked water-blocking finish or a water-repellant finish. Cross-linked water-blocking finishes are known to comprise compounds that only swell in contact with water. Water-repellant finishes are known to consist of compounds that repel water. Therefore, if the aramide fibers are provided with a cross-linked water-blocking or water-repellant finish, the fibers only become accessible for recycling after the mentioned finish has been removed.
JP-A-59 106 570 proposes that the fibers be treated in a low-temperature plasma to remove the water-repellant finish from textiles. However, this procedure is expensive in light of the vacuum equipment required for this purpose.
One disclosure of JP-A-04 202 853 for removing the water-repellant finish from aramide fibers involves treating the fibers through mechanical abrading with a spiked lattice or emery paper, but preferably with sandblasting. However, the danger with these procedures is that the aramide fiber becomes damaged. Another disclosure in JP-A-04 202 853 teaches eluting with a solvent, but provides no indication as to the type of solvent. Therefore, the expert must first figure out which water-repellant finish was used on the aramide fibers. Then, the expert must find a solvent in which this water-repellant finish is soluble, and finally, this solvent must not dissolve the aramide fibers.
Therefore, an object of this invention is to provide a procedure for removing a cross-linked water-blocking or water-repellant finish from aramide fibers that is easy to execute and does not damage the aramide fibers.
These and other subjects are achieved by a procedure for removing a water-insoluble finish from aramide fibers wherein the aramide fibers are present as a short-cut, random fiber or flat textile material, and treated with an agent that comprises at least one hydrophilic fluid. In this case, the term hydrophilic fluid refers to a hydrophilic liquid or hydrophilic gas within the framework of this invention. Further, being treated within the framework of this invention implies that the aramide fibers are treated once or repeatedly with the agent containing at least one hydrophilic fluid.
The procedure according to the invention removes the water-insoluble finish from the aramide fibers to at least the extent that the fibers treated according to the invention can be recycled.